1. Field
Example embodiments of the following description relate to a plasma generation method and apparatus, and more specifically, to a method and apparatus for sterilization and deodorization of attached bacteria under the condition that steam or fine droplets of water are present.
2. Description of the Related Art
Recently, the requirements of air quality control in living environments, such as, sterilization or deodorization, have become more stringent due to the increase in individuals suffering from atopy, asthma, and allergies, or the increase in the risk of infectious diseases, represented by the explosive spread of new types of influenza. Further, as society becomes increasingly affluent, the amount of storage food increases or an opportunity to store leftovers increases, and thus, the importance of controlling an environment in the storage equipment, such as a refrigerator, increases.
In order to control air quality in living environments, physical control generally using a filter was conventionally executed. Through physical control, relatively large dust floating in air and/or bacteria or viruses may be trapped according to sizes of filter holes. Further, activated carbon having anhydrous absorption sites may trap odorous molecules. However, since, in order to trap such substances, air in a space of a target object to be controlled needs to completely pass through the filter, the size of the apparatus must be large, the maintenance cost required to replace the filter is increased, and the apparatus has no effect upon attached particles. Therefore, in order to achieve sterilization and deodorization of the attached particles, chemical active species may be discharged to a space desired to be sterilized or deodorized. When a medicine is distributed, or an aromatic or a deodorizer is discharged, active species need to be prepared in advance and periodic supplement of the active species is indispensable. On the other hand, units which generate plasma in the atmosphere and attempt sterilization and deodorization, using chemically active species generated, due to plasma generation, have recently been increasingly proposed.
Technology for generating plasma in the atmosphere through discharge and achieving sterilization and deodorization by ions or radicals (hereinafter, referred to as active species) generated thereby, may be classified into two types, described below.
(1) A passive plasma generation apparatus, which causes bacteria or viruses floating within the atmosphere (hereinafter, referred to as floating bacteria) or odorous materials (hereinafter, referred to as odors) to react with active species within a restricted volume in the apparatus (for example, Japanese Patent Laid-open Publication No. 2002-224211); and
(2) An active plasma generation apparatus, which discharges active species generated by a plasma generation unit into a closed space (for example, a living room, a bath room, the inside of a car, etc) having a larger volume than the passive plasma generation apparatus, and causes the discharged active species to react with floating bacteria or odors due to collision with the floating bacteria or odors in the atmosphere (for example, Japanese Patent Laid-open Publication No. 2003-79714).
The passive plasma generation apparatus may be advantageous in that high sterilization and deodorization of the air is expected through generation of active species of a high concentration due to generation of plasma in a small volume. However, the passive plasma generation apparatus may be disadvantageous in that the floating bacteria or odors need to be introduced into the apparatus, and thus, the size of the apparatus is increased, ozone as a byproduct due to plasma generation is generated, and separate installation of a filter to absorb or decompose ozone to prevent ozone from leaking to the outside of the apparatus is required.
In addition, the active plasma generation apparatus may be advantageous in that the size of the apparatus is relatively reduced, and sterilization of bacteria attached to the surfaces of clothes or household goods (hereinafter, referred to as attached bacteria), or decomposition of odors absorbed to the surfaces, is expected in addition to sterilization of floating bacteria or decomposition of odors in air. However, the active plasma generation apparatus may be disadvantageous in that the concentration of active species is decreased due to diffusion of the active species into a considerably large closed space, as compared with the volume of the apparatus, and thus, sterilization and deodorization are expected only upon active species having a long life. Consequently, deodorization effects are scarcely expected in a space having a high concentration of odors (concentration 10,000 times greater than the concentration of the active species).
As described above, the passive plasma generation apparatus exhibits effects restricted to floating bacteria or odors contained in an air flow introduced into the apparatus, and the active plasma generation apparatus exhibits effects upon floating bacteria, attached bacteria, and odors having a low concentration. Further, conventional plasma generation apparatuses may be disadvantageous in that an amount of generated ions or radicals is reduced due to lowering of the performance of the plasma generation apparatus in a high-humidity state. That is, the conventional plasma generation apparatuses may achieve either sterilization of floating bacteria and deodorization in a high-humidity state, or sterilization of floating bacteria and attached bacteria having a low concentration and deodorization of attached odors having a low concentration in a high-humidity state.
However, there are several situations in daily life in which both sterilization of attached bacteria and deodorization of odors of a high concentration are desired to be simultaneously achieved under the condition that steam or fine droplets of water are present in a high-humidity environment. Typically, there are home appliances for treating water. For example, a washing machine is generally in a high humidity state, various attached bacteria are present on the surface of a tub, and odors generated due to remaining water or decomposition of a detergent occur within the washing machine. Further, various bacteria or odors generated due to remaining food waste may be present within a dish washer.